1.) The easy and heavy way to do this is to go use YAST (via GUI or ncurses):

YAST then -> System then -> Language

In
the language list you can pick whichever language you want to install
character font support but in this example we focus on CJK /or Chinese,
Japanese, Korean Languages.

Once
you click Chinese, Japanese, Korean Languages, press ok and it will
start downloading and installing the packages, this can take awhile as
opensuse will download a lot of packages and still depends on your
machine and net connection too

The
Problem or rather issue with this is it will install everything with the including the kitchen sink approach, it will install so much packages than
needed or rather what i call an overkill to support
so many fonts and packages for the chosen languages, in the second
option i will explain a more leaner way to install CJK language
character support and break it down to each of the CJK languages

2.) This second option will be using the Command Line only no GUI, issue command in terminal:

In
this one command it will install Chinese, Japanese, Korean Font
support, below you can choose what to install for CJK support, lets you
wanted to install just a leaner version for Japanese or Korean you can
just install:

Chinese: Actually the chinese packages include several language support including japanese and korean but only partial support in
arphic-ukai-fonts arphic-uming-fonts, to show what I meant on what
languages are exactly supported in the chinese package details:

arphic-ukai-fonts: contain both Big5 and GB2312 charsets plus some european characters.
Currently it fully supports the following charsets:
ISO8859-1,2,3,4,7,9,10,13,14,15 Big5 GB2312-80 Bopomofo Extensions for
Hakka, Minnan (Unicode 4.0) and MBE variants using the Stylistic
Alternatives (salt) feature from the OTF spec.
Partly support is implemented for: HKSCS CNS 11643 GB18030 Japanese
Korean

arphic-uming-fonts:
contain both Big5 and GB2312 charsets plus some european
characters.
Currently it fully
supports the following
charsets:
ISO8859-1,2,3,4,9,10,13,14,15 Big5 GB2312-80 HKSCS 2004 Bopomofo
Extensions for Hakka, Minnan (Unicode 4.0) and MBE variants using the
Alternatives (aalt) feature from the OTF spec.
Partly support is implemented for: CNS 11643 GB18030 Japanese Korean

Anyways to install issue command in terminal:

# zypper install arphic-ukai-fonts arphic-uming-fonts

Alternatively
there is the Google SANS NOTO Fonts you can just install the
noto-sans-cjk-fonts: which contains Chinese, Japanese, Korean Font
Support from google sans noto CJK fonts, issue command in terminal:

# zypper install noto-sans-cjk-fonts

However
this font package though is about 70+MB Download but it will install
for support on all 3 CJK languages, you can choose to just install this
or install it with the other packages mentioned above, but this by
itself can support all 3 langauges, though with a bigger download size,
however even if you install all the packages mentioned in this article,
it still wont be as much as the gargantuan amount of packages opensuse
will install with option 1 mentioned earlier with GUI and ncurses YAST
way.

NOTES:

-
All fonts packages mentioned here are available from
openSUSE-Tumbleweed-Oss REPO or your respective opensuse version OSS
REPO, so just make sure you have the OSS repository enabled in your
zypper repo list

- List fonts with this command:

$ fc-list

- Rebuilds cached list of fonts (after installing fonts and it doesnt work, run this command):

$ fc-cache -fv

- You could just install everything mentioned here and rebuild the cache font list in one go with this command: